T cells play a role in fighting coronavirus; COVID-19 affects children differently

FILE PHOTO: The ultrastructural morphology exhibited by the 2019 Novel Coronavirus (2019-nCoV), which was identified as the cause of an outbreak of respiratory illness first detected in Wuhan, China, is seen in an illustration released by the Centers for Disease Control and Prevention (CDC) in Atlanta, Georgia, U.S. January 29, 2020. Alissa Eckert, MS; Dan Higgins, MAM/CDC/Handout via REUTERS

NEW YORK (Reuters) - The following is a brief roundup of some of the latest scientific studies on the novel coronavirus and efforts to find treatments and vaccines for COVID-19, the illness caused by the virus.

Immune system’s T cells play a role in attacking the coronavirus

While the immune system's B cells make antibodies that block the novel coronavirus, its T cells provide another line of attack, according to new research. Researchers found that T cells from recovered patients can target the virus. That is promising news for vaccine developers because it is "consistent with normal, good, antiviral immunity," Shane Crotty, from the Center for Infectious Disease and Vaccine Research at the La Jolla Institute for Immunology in California, told Reuters. "The types of immune responses targeted by many candidate vaccines are now shown to be the types of immune responses seen in COVID-19 cases that successfully recovered from the disease." Furthermore, some people who never had COVID-19 nonetheless had T cells that could attack the virus, Crotty's team reported on Thursday in the journal Cell. This suggests that past exposure to other coronaviruses (such as those that cause the common cold) had somehow primed their T cells to recognize and attack this new coronavirus. That might influence their susceptibility to COVID-19 disease, he said, either preventing them from getting infected or from developing severe disease. (bit.ly/36bRpSD)

Coronavirus affects adults and children differently

Children appear to have much lower rates of infection with the new coronavirus than adults, but most reports on COVID-19 in youngsters have focused only on small groups. A team of Chinese researchers has analyzed data from 24 earlier studies involving a total of nearly 2,600 children with COVID-19, enabling them to shed light on ways in which the virus acts differently in pediatric patients. They reported on Sunday in the Journal of Medical Virology that the most common laboratory test abnormality observed in adults was a low level of immune cells called lymphocytes (B cells and T cells). This condition, known as lymphopenia, developed in up to 80% of adults but in less than 10% of children. On the other hand, children - particularly infants - were more likely to have elevated levels of cardiac enzymes that indicate heart injury. They also found additional differences. The rates of severe illness and critical illness in adults were 14% and 5%, respectively (according to earlier reports). That compared with 4.4% and 0.9% in children. Fever occurred in up to 99% of adults but in 43% of children; cough in up to 82% of adults but 43% of children. Shortness of breath and acute respiratory distress syndrome (ARDS) were rare in children, but digestive tract symptoms like diarrhea were more common in kids than in grownups. (bit.ly/3dXpTLf)

Coronavirus can infect patients taking hydroxychloroquine

Taking hydroxychloroquine for other medical conditions might not protect against the new coronavirus, French doctors say. The drug had nearly become a standard of care for patients with COVID-19 in many hospitals, even though randomized trials have not yet confirmed its value. But people around the world use decades-old hydroxychloroquine to treat malaria as well as inflammatory conditions like lupus and rheumatoid arthritis, and researchers are seeing occasional cases of coronavirus infection in these patients despite long-term use of the drug. A report on Sunday in the Journal of Antimicrobial Chemotherapy describes two such patients, one with rheumatoid arthritis and the other with a condition called mixed connectivitis. The authors say they also know of at least three other patients in Italy who became sick with COVID-19 despite taking hydroxychloroquine for chronic arthritis. "Patients actually taking long-term hydroxychloroquine are potentially immunosuppressed patients since they are living with chronic inflammatory diseases and thus do not represent the general population exposed to COVID-19," the French doctors acknowledge. "However, these observational data are not in favor of a universal protective effect of hydroxychloroquine." (bit.ly/3cDC7bH)

New barcoding technique can help process 100,000 screening tests per day

A big challenge in preventing the spread of the new coronavirus is to identify and quarantine infected people who do not have symptoms. Laboratory workers can test blood samples from thousands of patients per day, still not enough to efficiently screen heavily populated areas. Now researchers at the OSU James Comprehensive Cancer Center in Columbus, Ohio say they have a way to screen over 100,000 samples per day. Their system, dubbed REMBRANDT, makes copies of the virus and introduces two barcodes that simplify patient identification. Barcoding of samples for screening is not new, but the OSU method takes a unique biochemical approach, aiming for a single barcoding and virus-copying step. "Barcodes on products in the supermarket, and molecular barcodes for REMBRANDT work the same way," investigator Richard Fishel told Reuters. "In this case, each patient has a unique combination of letters that allows for their simplified identification. With ten Next Generation sequencing machines, REMBRANDT can test every Ohio resident for COVID-19 infection every 10 days - an important step in contact tracing and reducing the spread of infection." His team's report, published on Sunday on the preprint server bioRxiv, has not yet been peer reviewed. "Our next step," Fishel said, "will be to collaborate with hospitals and public health departments to clinically validate REMBRANDT and make it available to a wider audience." (bit.ly/2Ax26mT)